Wait you bough both MH and HPS? What light fixture you got for them? I have the same set!!Using an aircooled hood to keep temps low,MH and HPS will get hotter than led!
Also to clear up that HPS+LED combo,it is coming around that it can bring sunlight-like budgrowth to indoor grows,so don't jump at anything without reading first,Nebula has quoted this somewhere on GWE :
A combination of HPS and LEDs seems to provide some of the best benefits of both - big yields plus high quality and potency. This may be because a combination of HPS plus LEDs more closely mimics the autumn sunlight that cannabis plants are exposed to in the wild.
No unless someone has more grows than Nebula under their belt,please consider not roaring out stuff that can hurt someones future grows!This guy just spent 100$ on HPS/MH fixture and he would have done great for 2 plants even 3 autos in there with his previous setup!!
Either way,you are now closer to bigger yields,better growth and bigger plants as the 600w HPS/MH is the most known to be used for efficiency!
I have since seeds run the MH at 16" (40-41cm to be exact) and the HPS at the flip again at 16" without a single issue besides heat sometimes..Then again if you have a good fixture or as you said will provide A/C to them you will do great!!
Combining a co2 unit with a A/C unit would be hard however,one works with high temps and the other lowers temps....Co2 works at 27+ celcius ,optimum 28-30C (even recorded at 32C in a totally sealed environment) and at a steady 1300+ ppm! You will achieve 28 easily with the mh if you don't have more that 300cfm exhaust!
It seems you aren't on a budget so slow down and get a setup dialed in,ask here,tell us what exactly you want to grow,what will u use for growing? the 32" tent? if so the 600w bulbs will kill anything in there pretty soon...It will be like a microwave lol!! A good footprint for 600w is 3x3 or 4x4 at the faar faaar end of it sits my tent at 4.5x4.5 !! Unless you have damn heavy exhaust which will automatically cancel your co2,an aircooled hood and an oscilating fan for circulation you will only have :
1.60m (63")
-6" reflector
-16" light distance
-10" pot height
That leaves you with 15" of veg growth and 15" of flower unless you train and position the plants in a way they are lower (Ofc people here can help you do this easily if you pay attention)
That shoud be a great project with even 4 squeezed and firmly trimmed autos in there mate!! For high yielding autos could get you quite a bunch of buds in there
